GB2128203A

GB2128203A - Greasing or dubbing leather and skins

Info

Publication number: GB2128203A
Application number: GB08325437A
Authority: GB
Inventors: Fritz Landbeck; Dr Rolf Leberfinger; Heinz-Peter Matschkal; Dr Paul Rathfelder
Original assignee: Schill and Seilacher AG
Current assignee: Schill and Seilacher AG
Priority date: 1982-10-15
Filing date: 1983-09-22
Publication date: 1984-04-26
Also published as: FR2534597B1; JPS5993800A; DE3238180C1; IT1170511B; GB2128203B; FR2534597A1; GB8325437D0; JPS6128720B2; IT8349153A0; US4470825A

Description

1 GB 2 128 203 A 1

SPECIFICATION

A process of greasing or dubbing leather and skins Lecithins have been known for many years as 70 valuable leather greasing agents or dubbins. For use in a liquor bath, the lecithins are emulsified with known anionic, cationic or non-ionogenic emulsifiers.

Frequently anionic, cationic and non-ionogenic liquor oils are also used in combination with lecithins.

Agents or dubbins for greasing or dubbing leather are described in a series of German Patents. The said agents consist of a mixture of lecithins and fatty oil or train-oil or blubber and in some patents of addition the agents vary by having a volume of water or slight amounts of soap orsulphonated oil added to the mixture. The aforesaid agents are described in detail in Main Patent DE-PS 514399 and additionally in Patents of Addition DE-PS 516 187, DE-PS 516 188, DE-PS 516 189 and DE-PS 522 041 appertaining thereto.

In Patent DE-OS 3101914 partially saponified lecithins with a claimed degree of saponification of 120to 140 in mixture with polyhydroxyl compounds (sugar and the like) are mentioned as textile, paper and leather additives which are particularly used in formulations with non-ionogenic or anion-active emulsifiers and also organic solvents.

Furthermore, in DE-AS 28 43 755 it has been proposed to use a hydroxylated phosphatide for the treatment of tanned leather in a liquor bath.

These Patents indicate that lecithin, by reason of its chemical structure (it consists of a fatty substance with polar groups), is well suited to be a leather greasing or dubbing agent. However, experience showsthat in emulsions itforms large micelles so that it can penetrate only incompletely into the leather. The use of lecithin is therefore restricted in practice, because it often results in inadequate greasing or dubbing of the leatherso thatthe resultant leather is stiffand harder 105 than desired.

According, it is necessary to use lecithin forthis purpose in a formulation which enablesthe leatherto be completely and uniformly penetrated bythe greasing or dubbing agent and the liquorsolution to be used up rationally and as completely as possible.

It has been found that a good and uniform absorp tion of lecithin bythe leatherfrom aqueous emulsion can be achieved in a simple manner if self-emulsifying reaction products of lecithins are used and, in 115 accordance with the present invention, if the selfemulsifying reaction products are lecithin salts which have been obtained by partial or complete neutralisation of industrial grade lecithins, obtained from vegetable oils and having acid numbers from 10 upto 40, with oxethylated fatty amines.

The said salts can be used either as additivesto the customary greasing or dubbing agents or as sole greasing or dubbing agent. When used with a relatively slight supply of grease, extremely soft, firmly-grained and smooth leather is obtained.

To produce the aforesaid lecithin salts, industrial grade lecithins, which are obtained from vegetable oils (for example, soya oil, rape oil, maize oil) and have acid numbers between 10 and 40, preferably 15 and 30, arewhollyor partially neutralised with oxethylated fatty amines. In addition to phosphatides the lecithins predominantly contain fats (triglycerides) the overall proportion of which generally lies at30 to 40 percent.

Preferablythe oxethylated fatty amines used to produce salts forthe process of the invention possess a saturated or unsaturated, straight or branched carbon chain consisting of 8 to 24 carbon atoms, preferably 12 to 18 carbon atoms, and a degree of oxethylation of 5 to 30 moles (preferably 15 to 25 moles) of ethylene oxide per mole of fatty amine.

To produce a leather greasing or dubbing agent in accordance with the invention, the two components, lecithin and fatty amine oxethylate, are mixed homogeneously at a temperature which lies above the melting point of the individual components and are cooled to room temperature in the appropriate circumstances.

In so doing, for a complete neutralisation of 1g of lecithin having acid numbers of 1 Oto 40,0.18- 0.71 moles of oxethylated fatty amine are used. Usually partial neutralisation is sufficient, for which purpose 30 to 50 percent of the amount of oxethylated fatty amine necessaryforthe complete neutralisation is used. In parts byweightthis means, depending on the acid number of the lecithin and the molecularweight of the oxethylated fatty amine, thatforthe complete neutralisation of 10 parts byweight of lecithin, 0.6- 12 parts byweight of oxethylated fatty amine are used. In practice, for partial neutralisation, 1 -3 parts byweight of oxethylated fatty amine are preferably used for 10 parts byweight of lecithin.

For use in thefatty liquor,the neutralisation product of the lecithin in accordance with the invention is pre-emulsified with water in the customary manner and then added to the liquor in the vat.

The invention will be described fu rther by reference to a number of examples. Example 1: 1000 parts byweight of a commercially available industrial grade soya lecithin with an acid numberof 20 are mixed homogeneously at 50'Cwith 150 parts by weight of an oleylaminoxethylate having 20 Moles of ethylene oxide so that partial neutralisation results.

Neutralised chrome-ox or chrome-bovine leather which has been re-tanned with mimosa is greased or dubbed with 7 percent of the neutralisation product (related to whitening of folding weight) in a liquor bath. Forthis the product is initially- as is customary practice- preemulsified with warm water and then added to the liquor bath. During a working time of 60 minutes, the grease or dubbin is completely absorbed bythe leather. The leather is re-worked a manner which is customary in the industry. The finished leather is exceptionally soft and displays fine, smooth and fixed graining. Example2: 1000 parts of a commercially available industrial grade soya lecithin with an acid number of 30 are mixed homogeneously at 500C with 200 parts of an oleylaminoxethylate having 20 moles of ethylene oxide so that partial neutralisation results. a) Pickled sheepskin fleeces are chrome-tanned in a manner customary in the industry and during the 2 GB 2 128 203 A 2 tanning theyare greased or dubbed in the same liquor bath with 8g ofthe neutralisation product per litre of solution. Forthis,the greasing ordubbing agentis pre-emulsified and addedtothe chrometanning bath.

Afteran operating ortransittime of 12 hours,the bath 70 no longercontains anygrease ordubbin, i.e. it has been completely absorbed bythe leather. The fleeces or skins are then further worked inthe industrially customary manner. The finished skins are excep- tionally pliant and soft to the touch. b) Chrome-tanned sheepskins are, subsequentto tanning, neutralised in fresh solution and greased or dubbed in the same bath with 7g of the neutralisation product per litre of solution. The greasing or dubbing agent is, forthis purpose, pre-emulsified and added to the solution. During a transittime of 60 minutes, the grease or dubbin is completely absorbed bythe leather. The skins arefurtherworked in the industrially customary manner and when finished are very pliant and airy. Example3: 1000 parts of a commercially available industrial grade soya lecithin with an acid number of 30 are mixed homogeneously at40'C with 150 parts of a coconut oil amine having 15 Moles of ethylene oxide so that partial neutralisation results. After cooling to 2WC, the product can be used as a fatty liquor. Re-tanned and neutralised sheep's leather or sheepskin in greased or dubbed with 10 percent of the neutralisation product (relates to folded orwhitened weight) in the liquor bath. Forthis, the product is previously emulsified with warm water and then added to the liquor bath. During a transittime of 40to 60 minutes,the grease or dubbin is completely

Claims

absorbed bythe leather. The leather isfurtherworked in the industrially customary manner. Thefinished sheet leather is exceptionally tearresistant and is soft and airyto handle ortouch. CLAIMS

1. A process of greasing or dubbing leather and skins in which selfemulsifying reaction products of lecithins are used as greasing or dubbing agent characterised in thatthe self-emulsifying reaction products are lecithin salts which have been obtained by partial or complete neutralisation of industrial grade lecithins, obtained from vegetable oils and having acid numbersfrom 10 upto 40, with oxethylated fatty amines.

2. A process as claimed in claim 1, characterised in that oxethylated fatty amines with a saturated or unsaturated, straight or branched chain of 8to 24 carbon atoms and a degree of oxethylation of 5to 30 Moles of ethylene oxide per Mole of fatty amine have been used to produce the lecithin salts.

3. A process as claimed in claim 2, characterised in that oxethylated fatty a mines with a saturated or unsaturated, straight or branched chain of 12to 18 carbon atoms and a degree of oxethylation of 15to 25 Moles of ethylene oxide per Mole of fatty acid have been used to produce the lecithin salts.

4. Aprocessasclaimed in claim 1,2or3, characterised inthatthe oxethylated fatty amines which are used to produce the lecithin salts are used in an amountfrom 30 to 50 percent of the 0.18to 0.71 Moles fatty amine necessary forthe complete neutra- lisation of 1 g of lecithin having an acid numberfrom 10to40.

5. A process of greasing or dubbing leather and skins substantially as hereinbefore described.

Printed for Her Majesty's Stationery Office byTheTweeddale Press Ltd., Berwick-upon-Tweed, 1984. Published atthe Patent Office, 25 Southampton Buildings, London WC2A lAY, from which copies may beobtained.

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